English: From Schaefer 2023. I upload here on wikimedia only the Figure 5 which shows the final constrains of SN 1181.

Abstract paper:

In 1181 AD, Chinese and Japanese observers reported an unmoving bright "Guest Star" in the constellation Chuanshe, visible for 185 days. In 2013, D. Patchick discovered what turned out to be a unique nebula surrounding a unique star, with the structure named "Pa 30", while subsequent workers made connections to mergers of white dwarfs, to the supernova subclass of low-luminosity Type Iax, and to the 1181 transient. Here, I provide a wide range of new observational evidence: First, detailed analysis of the original Chinese and Japanese reports places the "Guest Star" of 1181 into a small region with the only interesting source being Pa 30. Second, the ancient records confidently place the peak magnitude as 0.0>Vpeak>−1.4, and hence peak absolute magnitude −14.5>MV,peak>−16.0 mag. Third, the Pa 30 central star is fading from B=14.9 in 1889, to B=16.20 in 1950, to B=16.58 in 2022. Fourth, recent light curves show typical variability with full-amplitude of 0.24 mag on time-scales of one day and longer, critically with no coherent modulations for periods from 0.00046--10 days to strict limits. Fifth, the spectral energy distribution from the far-infrared to the ultraviolet is a nearly-perfect power-law with Fν∝ν0.99±0.07, observed luminosity 128±24 L⊙, and absolute magnitude MV=+1.07. I collect my new evidences with literature results to make a confident case to connect the East-Asian observations to a supernova, then to Pa 30, then to a low-luminosity Type Iax SN, then to the only possible explosion mechanism as a merger between CO and ONe white dwarfs.

Figure 5:

SN 1181 position from all constraints. The three sets of constraints (the deep cyan regions in each of Figs. 2, 3, and 4) form a joint constraint on the SN 1181 position, as shown by the cyan region with black edges in this figure. The details of this figure are the same as for the earlier figures. The final shape is convoluted because of the circular constraints from Fig. 3 (the nearness to candidate fifth stars of Chuanshe). The final error region has an area of roughly 15 square-degrees. The position of Pa 30 is near one of the edges, but this is fine as the Chinese astronomers would have reported such a guest star as being inside Kui whether it is near the edge or near the centre. The main takeaway from this figure is that Pa 30 is definitely inside the small final positional region for SN 1181.